Population-based incidence of herpes zoster after introduction of a publicly funded varicella vaccination program

Cost-Effectiveness of Varicella Vaccination for 1-4-Year-Olds in Shanghai, China

INTRODUCTION

Varicella has not yet been included in the National Immunization Program (NIP) in China, and varicella vaccination strategies vary by region. To determine the optimal varicella vaccination strategy in Shanghai, China, the cost-effectiveness and 5-year costs of 5 immunization scenarios were analyzed.

METHODS

A static decision tree-Markov model was developed in 2022 to assess the cost-effectiveness and 5-year costs of voluntary and routine varicella vaccination programs in the 2019 birth cohort in Shanghai from a societal perspective. Parameters were collected in 2022 from the varicella surveillance system, a questionnaire survey of 414 guardians of patients with childhood varicella, and semi-structured interviews with 20 experts on varicella outbreaks from different institutions in Shanghai. The outcomes included varicella cases avoided, quality-adjusted life year (QALY) loss, and incremental costs per QALY (ICER). The 5-year costs were compared with local medical expenditures.

RESULTS

Among the 5 scenarios, one dose of routine varicella vaccination was the most cost-saving (USD 70.2) and cost-effective (Dominant) with a 5-year immunization expenditure of USD 9.9 million. Two doses of routine varicella vaccination had the highest QALY (29.9), and its ICER (USD 791.9/QALY) was below the willingness-to-pay threshold (USD 5,203-23,767/QALY). The 5-year immunization expenditure was USD 19.8 million. The effectiveness and price of vaccines, vaccination coverage, and per capita income are the 4 main factors that affect ICERs.

CONCLUSIONS

In Shanghai, the 2 doses of routine varicella vaccination strategy for 1- and 4-year-olds with a 95% coverage rate was found to be the optimal varicella immunization strategy.

Liver Cirrhosis Increases the Risk of Herpes Zoster: A Nationwide Population-Based Cohort Study

INTRODUCTION

Limited data are available regarding the association between liver cirrhosis (LC) and the risk of herpes zoster (HZ). This study aimed to determine the risk of HZ in patients with LC.

METHODS

HZ was defined as the presence of the International Classification of Diseases-10th revision code for HZ and concomitant prescription of antiviral medication. The incidence rates and standardized incidence ratios (SIRs) of HZ in patients with LC were analyzed using data from the Health Insurance Review and Assessment Service in Korea claims database from 2009 to 2019.

RESULTS

A total of 504,986 Korean patients with LC were included. The mean age was 52.4 years, and 60.8% were men. Chronic hepatitis B was the most common cause of LC. The incidence rates for HZ and HZ-related hospitalization were 21.6 of 1,000 and 1.81 of 1,000 person-years, respectively. The SIRs for HZ and HZ-related hospitalization were 1.09 (95% confidence interval [CI]: 1.08-1.09) and 1.48 (95% CI: 1.44-1.52), respectively, which were significantly higher than those in the general population. Patients with LC aged 20-29, 30-39, and 40-49 years had SIRs for HZ of 1.41 (95% CI: 1.33-1.48), 1.16 (1.13-1.19), and 1.17 (1.13-1.19), respectively. In multivariable analysis, woman (adjusted hazard ratio [AHR]: 1.48), steroid (AHR: 1.20), immunosuppressant use (AHR: 1.26), and combined comorbidities were associated with an increased risk of HZ among patients with LC.

DISCUSSION

Patients with LC, particularly those who are not currently recommended for HZ vaccination, were at an increased risk of HZ and HZ-related hospitalization compared with the general Korean population.

The Impact of Universal Varicella Vaccination on Herpes Zoster Incidence in the United States: Comparison of Birth Cohorts Preceding and Following Varicella Vaccination Program Launch

When the US varicella vaccination program was introduced in 1995, its impacts on the epidemiology of herpes zoster (HZ) were not precisely known. We used a large claims database to examine HZ incidence in the US during 1998-2019 among persons aged ≥30 years (the prevaccine cohort, born before 1990), and aged 1-29 years (includes the postvaccine cohort, born since 1990). We defined incident HZ as the first instance of an outpatient or emergency department (ED) claim with an HZ diagnostic code. Additionally, we examined the proportion of HZ visits among all ED visits as a complementary method to assess for healthcare-seeking artifacts in the findings. In persons aged ≥30 years (prevaccine cohort), we observed age-specific increases in HZ incidence during the earlier study years, with decelerations in later years, starting in 2007 with oldest age groups. Similar patterns were seen when we examined HZ visits as a proportion of all ED visits. For persons aged 1-29 years, age-specific HZ incidence increased early in the study period for the oldest age groups who were born prevaccine, but later declined in a stepwise pattern once each age group was comprised of persons born in the postvaccine period. Our results, corroborated with previously published studies, do not support prior modeling predictions that the varicella vaccination program would increase HZ incidence among adult cohorts who previously experienced varicella. Our findings also suggest that continued declines in age-specific HZ incidence as varicella-vaccinated cohorts age are likely.

An Analysis of Spontaneously Reported Data of Vesicular and Bullous Cutaneous Eruptions Occurring Following Vaccination with the Adjuvanted Recombinant Zoster Vaccine

Introduction

With the approval of the adjuvanted recombinant zoster vaccine (RZV; Shingrix, GSK) in October 2017, GSK established enhanced safety surveillance measures to allow prompt identification of potential safety signals not observed during clinical development. In Germany, cases of vesicular and bullous cutaneous eruptions following RZV vaccination were reported.

Objective

Our objective was to search and analyse 2.5 years of worldwide spontaneously reported post-marketing data for vesicular and bullous cutaneous eruptions, represented by adverse events suggestive of (1) herpes zoster (HZ) and (2) non-HZ vesicular and bullous cutaneous eruptions, that occurred following RZV vaccination.

Methods

We conducted a descriptive analysis of all identified reports of HZ and non-HZ vesicular and bullous cutaneous eruptions following RZV vaccination and an observed versus expected (O/E) analysis of reports of HZ that met criteria of varicella zoster virus (VZV) reactivations following RZV vaccination (i.e., time to onset [TTO] of the event < 30 days or missing after any dose).

Results

Until the data lock point, 32,597,779 RZV doses had been distributed globally. There were 2423 reports of HZ (including complications) identified, of which 645 met the criteria of possible vaccination failure (i.e., TTO of the event ≥ 30 days or missing following a complete RZV vaccination schedule). The O/E analysis of 1928 reports assessed as possible VZV reactivations indicated that the observed number of cases was lower than that expected in the general population. Additionally, 810 reports of non-HZ vesicular and bullous cutaneous eruptions were identified, including injection site rashes attributed to the vaccine’s reactogenicity.

Conclusion

This review of spontaneously reported post-marketing data did not raise safety concerns regarding the occurrence of vesicular and bullous cutaneous eruptions following vaccination with RZV.

Supplementary Information

The online version contains supplementary material available at 10.1007/s40264-021-01118-3.

Shingles is a disease caused by reactivation of the chickenpox virus. It mostly affects adults aged 50 years and older and patients of all ages who have an impaired immune system. Diagnosis of shingles is often based only on the presence of symptoms such as a typical rash and pain. However, rashes can have various other causes (e.g., allergies, autoimmune diseases, and infections). Consequently, rashes with other causes may be misdiagnosed as shingles. Adults at increased risk of shingles and/or aged 50 years and older may be vaccinated with Shingrix (GSK, Belgium) to protect them from shingles and its complications. Since Shingrix became available in Germany, blister-like skin rashes have been reported that occurred shortly after vaccination. We searched the GSK safety database for reports of blister-like skin rashes that occurred following vaccination with Shingrix and that were spontaneously reported from countries where Shingrix was first marketed. To analyse these reports of rashes, we described the reports that we retrieved, we performed a statistical analysis to quantify whether the number of events assessed as reactivations of the chickenpox virus following Shingrix vaccination was higher than the number of reactivations that would be expected in the general population, and we described possible explanations for the observed rashes and underlying disease mechanisms. Our analyses did not raise safety concerns related to the onset of these rashes after vaccination with Shingrix. This paper raises awareness about the varying causes of rashes since a shingles-like rash that onsets shortly after vaccination with Shingrix is not necessarily caused by vaccination. In conclusion, this analysis shows that caution is needed when evaluating rashes in older adults and that all potential contributing factors (e.g., pre-existing diseases, medication, vaccination) should be considered.

Routine varicella vaccination program and hospitalization for herpes zoster in Japan

Whether reducing exposure to varicella by the implementation of the routine varicella vaccination program for children leads to increased incidence of herpes zoster (HZ) remains controversial. The aim of the present study was to identify the trend in the hospitalization associated with HZ before and after the introduction of routine varicella vaccination by using nationally representative data from an inpatient database in Japan. Data were obtained on the number of inpatients hospitalized for HZ from the "Survey on the effect of the introduction of Diagnosis Procedure Combination (DPC) database" and the total population in Japan from the Population Estimates created by the former Statistics Bureau between fiscal years 2013 and 2018. The data from the DPC hospitals only and all hospitals in the survey were analyzed separately. The trends in the annual incidence of HZ hospitalization were identified. The trends in the annual hospitalization for HZ per 100,000 persons were then analyzed by age group (0-20, 21-40, 41-60, 61-79, and ≥80 years of age). The annual number of hospitalizations for HZ was approximately 20,000 in the DPC hospitals and 25,000 in all hospitals, showing no upward trend. The age-specific annual hospitalization rate for HZ did not increase in all the age groups. As age increased, the hospitalization rate also increased. This study presents no upward trend in the hospitalizations for HZ after the implementation of the routine varicella vaccination program in Japan.

Validation of algorithms using International Classification of Diseases for the identification of herpes zoster episodes requiring hospitalization in Quebec, Canada

OBJECTIVE

We determined secular changes in the incidence of hospitalizations due to herpes zoster (HZh) and assessed the validity of HZ International Classification of Diseases (ICD) code algorithms for identifying HZh in a region of Quebec, Canada.

METHODS

We performed a validation study as part of a retrospective cohort study of adult HZ patients hospitalized at Centre Hospitalier Universitaire de Sherbrooke during 2000-2017. Cases were identified using ICD codes from an inpatient administrative database. HZ cases identified by ICD-9 (053.xx) and ICD-10 (B02.x) codes were chart-confirmed, and performance characteristics of ICD code algorithms were calculated (positive predictive value [PPV] and sensitivity).

RESULTS

Overall, 1314 hospitalizations with HZ diagnosis (HZh) with or without complications were identified during 2000-2017. Among the hospitalizations, 526 (44.4%) were due to active HZ disease or a complication related to a recent or previous HZ episode. These hospitalizations were due to active disease at the time of admission (340/526, 64.6%), HZ that developed during hospitalization (120/526, 22.8%), or a complication directly related to a recent or previous HZ episode (66/526, 12.6%). PPV was significantly higher when HZ was the primary diagnosis (276/310, 89%, 95% confidence interval [CI]: 85-92%) than when HZ was a secondary diagnosis (254/928, 27%, 95% CI: 25-30%) (p < 0.0001), and the PPV of a first secondary diagnosis (84/140, 60.0%, 95% CI: 51.3-68.2%) was higher than that of other secondary diagnoses (203/794, 25.6%, 95% CI: 22.6-28.8%) (p < 0.0001). An algorithm combining ICD codes and antiviral usage demonstrated the best sensitivity (86.3%, 95% CI: 83.1-89.1%) and PPV to identify HZh (100%, 95% CI: 99.2-100%). Poisson regression revealed no significant changes in HZh over time (incidence rate ratio: 0.98, 95% CI: 0.92-1.04%; p = 0.5).

CONCLUSION

HZh incidence was stable over time. Prescription of antivirals might be a useful addition to ICD codes to identify HZh cases from administrative databases.

A systematic literature review of herpes zoster incidence worldwide

We conducted a systematic review to characterize the incidence rate of herpes zoster (HZ) in the general population, specifically in individuals ≥50 years of age. A total of 69 publications were included in the review. We found a cumulative incidence of HZ ranging from 2.9–19.5 cases per 1,000 population and an incidence rate of HZ ranging from 5.23–10.9 cases per 1,000 person-years. The cumulative incidence (3.22–11.2 versus 2.44–8.0 cases per 1,000 population) and incidence rates (6.05–12.8 versus 4.30–8.5 cases per 1,000 person-years) were higher in females than males. Studies revealed a trend of increasing incidence of HZ with increasing age and over time. Variations in incidence estimates can be attributed to the various study designs, case ascertainments, age distributions of the population and year of the study. HZ is associated with a substantial disease burden and is expected to increase due to population aging.

Effect of the varicella vaccination implementation on the development of herpes zoster in children and adolescents

Herpes zoster (HZ) is an infectious disease caused by latent varicella-zoster virus reactivation. There are conflicting reports on the varicella vaccine's effect on the incidence of HZ in children and adolescents. This study aimed to determine the impact of the single dose of varicella vaccination on HZ prevalence during childhood and adolescence. The study included children and adolescents aged <18 years who presented to the dermatology outpatient clinic between 2005 and 2019 and were diagnosed with HZ. Considering that the universal vaccination program started to be implemented in Turkey in 2013, non-vaccinated cases in the prevaccination period, vaccinated cases in the postvaccination period, and non-vaccinated patients in the postvaccination period were compared in terms of HZ prevalence and demographic features. After the initiation of the varicella vaccination program, the prevalence of HZ was found to decrease by 24.7% in all. The HZ prevalence was significantly reduced in vaccinated children, while the rate of decrease in non-vaccinated children was low (58.6% and 16.4%, respectively). The median age of the non-vaccinated cases in the postvaccination period (10 [min 0.5-max 17] years) was significantly higher compared to the other groups (p < 0.001). The number of cases aged <2 years was the highest in the vaccinated group (p < 0.001). Administration of a single dose of varicella vaccine was insufficient to decrease the prevalence of HZ <18 years of age. In the post-vaccination period, the frequency of HZ in unvaccinated cases increased in adolescence. In vaccinated children, HZ seems to develop at an earlier age.

Herpes zoster in older adults in Ontario, 2002-2016: Investigating incidence and exploring equity

Older adults are at increased risk of herpes zoster (HZ) and post-herpetic neuralgia (PHN) and HZ vaccines are available to help prevent infection. The objective of our study was to provide updated data on incidence of HZ and PHN related to clinical and demographic factors in older adults to inform immunization practices. We conducted a population-based, retrospective cohort study and included all cases of HZ seen in outpatient, emergency department, and hospital settings for adults aged 65 years and over between April 1, 2002 to August 31, 2016 in Ontario, Canada. We calculated the incidence of HZ and PHN, and estimated the proportion within each subgroup that developed PHN. We also assessed incidence by neighbourhood-level income quintile before and after the availability of vaccine for private purchase. The average annual incidence of HZ in any setting was 59.0 per 10,000 older adults, with higher incidence in outpatient as opposed to hospital settings. Incidence was higher in the oldest age groups, females, and those classified as immunocompromised or frail. Relative to the pre-vaccine era, the disparities in incidence of HZ by neighbourhood-level income increased, with higher rates of HZ and PHN seen in those residing in lower income quintiles. Additional prevention efforts should be targeted toward adults who are immunocompromised, frail, and those living in lower socioeconomic quintiles. Future work should assess the impact of the zoster vaccine program with a particular focus on equity in the publicly-funded era.

What We Know Now: An Economic Evaluation of Chickenpox Vaccination and Dose Timing Using an Agent-Based Model

OBJECTIVES

The value of chickenpox vaccination is still debated in the literature and by jurisdictions worldwide. This uncertainty is reflected in the inconsistent uptake of the vaccine, where some countries offer routine childhood immunization programs, others have targeted programs, and in many the vaccine is only privately available. Even across the countries that have universal funding for the vaccine, there is a diversity of schedules and dosing intervals. Using an agent-based model of chickenpox and shingles, we conducted an economic evaluation of chickenpox vaccination in Alberta, Canada.

METHODS

We compared the cost-effectiveness of 2 common chickenpox vaccination schedules, specifically a long dosing interval (first dose: 12 months; second dose: 4-6 years) and a short dosing interval (first dose: 12 months; second dose: 18 months).

RESULTS

The economic evaluation demonstrated a shorter dosing interval may be marginally preferred, although it consistently led to higher costs from both the societal and healthcare perspectives. We found that chickenpox vaccination would be cost-saving and highly cost-effective from the societal and healthcare perspective, assuming there was no impact on shingles.

CONCLUSION

Chickenpox vaccine was cost-effective when not considering shingles and remained so even if there was a minor increase in shingles following vaccination. However, if chickenpox vaccination did lead to a substantial increase in shingles, then chickenpox vaccination was not cost-effective from the healthcare perspective.

Effectiveness and cost-effectiveness of vaccination against herpes zoster in Canada: a modelling study

BACKGROUND

Two vaccines against herpes zoster are currently authorized for use in Canada: the recombinant subunit zoster vaccine and live attenuated zoster vaccine. We compared the effectiveness and cost-effectiveness of these 2 vaccines.

METHODS

We used a decision analytic static cohort model parametrized with Canadian epidemiologic and economic data. We performed the economic analysis from the health care system perspective, using a lifetime horizon and a 3% discount rate for costs and benefits. The primary outcome was the incremental cost per quality-adjusted life-year (QALY) gained, relative to no vaccination. We ran 30 000 simulations varying all model parameters, including vaccine costs, efficacy and waning.

RESULTS

The number needed to vaccinate (NNV) was higher for the live attenuated zoster vaccine than for the recombinant subunit zoster vaccine for all herpes zoster-related events at all ages. For example, in persons exactly 65 years old, for herpes zoster, median NNV was 21 (90% uncertainty interval [UI] 13-31) versus 8 (90% UI 6-18), and for postherpetic neuralgia, NNV was 64 (90% UI 33-93) versus 31 (90% UI 23-73). For the recombinant vaccine, the median cost-effectiveness ratios varied between cost-saving and $25 881 per QALY gained for adults aged 50 years or older. For the live vaccine, the cost-effectiveness ratios varied between cost-saving and $130 587 per QALY gained and were less than $45 000 per QALY gained only for those 65 to 75 years old. Given its higher efficacy, we estimated that the cost for the complete series of the recombinant vaccine could be $150 to $200 more than the cost of the live vaccine and still be considered cost-effective.

INTERPRETATION

Our model predicted that the recombinant subunit zoster vaccine is likely cost-effective in Canada for adults 60 years or older, and is likely more cost-effective than live attenuated zoster vaccine. These results have informed updated national and provincial recommendations on herpes zoster vaccination.

Risk Factors for Herpes Zoster Infection: A Meta-Analysis

Background

The burden of herpes zoster (HZ) is significant worldwide, with millions affected and the incidence rising. Current literature has identified some risk factors for this disease; however, there is yet to be a comprehensive study that pools all evidence to provide estimates of risk. Therefore, the purpose of this study is to identify various risk factors, excluding immunosuppressive medication, that may predispose an individual to developing HZ.

Methods

The literature search was conducted in MEDLINE, EMBASE, and Cochrane Central, yielding case control, cohort, and cross-sectional studies that were pooled from January 1966 to September 2017. Search terms included the following: zoster OR herpe* OR postherpe* OR shingle* AND risk OR immunosupp* OR stress OR trauma OR gender OR ethnicity OR race OR age OR diabetes OR asthma OR chronic obstructive pulmonary disease OR diabetes. Risk ratios (RRs) for key risk factors were calculated via natural logarithms and pooled using random-effects modeling.

Results

From a total of 4417 identified studies, 88 were included in analysis (N = 3, 768 691 HZ cases). Immunosuppression through human immunodeficiency virus/acquired immune deficiency syndrome (RR = 3.22; 95% confidence interval [CI], 2.40–4.33) or malignancy (RR = 2.17; 95% CI, 1.86–2.53) significantly increased the risk of HZ compared with controls. Family history was also associated with a greater risk (RR = 2.48; 95% CI, 1.70–3.60), followed by physical trauma (RR = 2.01; 95% CI, 1.39–2.91) and older age (RR = 1.65; 95% CI, 1.37–1.97). A slightly smaller risk was seen those with psychological stress, females, and comorbidities such as diabetes, rheumatoid arthritis, cardiovascular diseases, renal disease, systemic lupus erythematosus, and inflammatory bowel disease compared with controls (RR range, 2.08–1.23). We found that black race had lower rates of HZ development (RR = 0.69; 95% CI, 0.56–0.85).

Conclusions

This study demonstrated a number of risk factors for development of HZ infection. However, many of these characteristics are known well in advance by the patient and clinician and may be used to guide discussions with patients for prevention by vaccination.

Evaluation of impact of one dose varicella vaccine on the incidence of chickenpox in Argentina

INTRODUCTION

Varicella, also known as chickenpox is one of the most common immunizable diseases. In 1998, the World Health Organization (WHO) recommended to incorporate this vaccine in the national immunization programs, which Argentina did in 2015.

OBJECTIVES

To describe the behavior of the varicella time series for the 2005-2017 period, and to evaluate the impact of the vaccine in Argentina.

METHODOLOGY

An ecological observational study was performed, using the varicella cases reported in the National Health Monitoring System, and the data of the National census as secondary data sources. A model based time series analysis of the notified varicella cases in Argentina was performed, using a Negative Binomial Mixed Model. For the verification of the vaccine impact, the 2005-2014 period was selected, and a prognosis for the following years was performed. Impact was evaluated by comparing the rates and confidence intervals between the predicted and observed values.

RESULTS

Argentina reported 1,775,587 varicella cases for the 2005-2017 period. The series exhibited seasonality, and, a decreasing trend in the number of cases was observed in 2016 and 2017. A reduction of the incidence rate after the implementation of the vaccine was observed. The transmission risk decreased in the country after vaccine implementation.

CONCLUSIONS

This study is the first concrete evidence of the varicella incidence decline after the implementation of a single dose application program in Argentina.

Do varicella vaccination programs change the epidemiology of herpes zoster? A comprehensive review, with focus on the United States

Introduction: Policy-makers in many countries have been wary of introducing varicella vaccination programs because of concerns that reduced exposures to varicella-zoster virus could increase herpes zoster (HZ) incidence. The U.S. introduced varicella vaccination in 1996 and has empiric evidence regarding this concern. Areas covered: This comprehensive review provides background emphasizing the epidemiology of varicella and of HZ in the U.S. before and after the introduction of their respective vaccines. The epidemiology is complex, and interpretation is complicated by methodologic challenges, by unexplained increases in age-specific HZ incidence that preceded varicella vaccination, and by introduction of vaccines for prevention of HZ. Nonetheless, observations from studies using different platforms and designs have yielded consistent findings, suggesting they are robust. Expert opinion: There has been no evidence that the U.S. varicella vaccination program increased HZ incidence in the general adult population over baseline trends. Furthermore, HZ incidence in children is declining. The U.S. experience can inform the development of new generations of models to predict HZ trends. More importantly, it provides reassurance for countries considering varicella vaccination that an effective program can reduce varicella morbidity and mortality while reducing the likelihood of HZ among children, and potentially, over time, across the entire population.

Varicella zoster virus vaccines: an update

Varicella zoster virus (VZV) is the etiological agent of varicella, a highly infectious, self-limiting disease with serious complications. The decline in cell-mediated immunity (CMI) that occurs with aging or immunodepression causes a reactivation of the latent VZV as herpes zoster (HZ). Prevention of VZV through varicella vaccination strategies allows to avoid the primary infection in newborns and susceptible subjects. Available monovalent and combined VZV vaccines are effective, safe and generally well tolerated. Universal varicella vaccination has significantly impacted on incidence, complications and deaths related to this disease. Prevention of HZ through vaccination is a priority to avoid the significant burden of its incidence and complications. Currently two HZ vaccines are available. The recombinant zoster vaccine (RZV), approved by the FDA in 2017 and Zoster Vaccine Live (ZVL) licensed in the United States by the FDA in 2006. The advisory committee on immunization practices (ACIP) preferentially recommends RZV. ZVL remains an option for prevention of HZ in immunocompetent adults aged ≥60 years, although the CMI tends to wane a few years after vaccination.

A clinico-epidemiological multicenter study of herpes zoster in immunocompetent and immunocompromised hospitalized children

Purpose

There are limited population-based data regarding herpes zoster in children. Thus we conducted a multi-institutional epidemiological analysis of herpes zoster in children and comparative analysis according to their immune status.

Materials and Methods

The study included 126 children under the age of 18 years who were hospitalized for herpes zoster at 8 hospitals in South Korea, between July 2009 and June 2015. The subjects were divided into 2 groups according to their immune status, and medical records were reviewed.

Results

There were 61 cases (48.4%) in the immunocompetent group and 65 cases (51.6%) in the immunocompromised group. Median age was older in immunocompromised group (11.4 vs. 8.6) (p<0.001). The mean duration of hospitalization was longer in immunocompromised group (11.0 vs. 6.6) (p<0.001). Patients were treated with oral or intravenous antiviral agents. A total of 12 in immunocompetent group were cured only by oral acyclovir. No treatment failure was found in both groups. Six immunocompromised patients had postherpetic neuralgia and 1 case was in immunocompetent group. In immunocompetent children, herpes zoster was likely caused by early varicella infection. There was no increase in progression of severity in both groups due to appropriate treatment.

Conclusion

Early initiation of therapy is necessary for those in immunocompromised conditions. And inactivated herpes zoster vaccination may be considered in immunocompromised adolescents in the future.

Incidence of Herpes Zoster Among Children: 2003-2014

BACKGROUND AND OBJECTIVES

After the 1996 introduction of routine varicella vaccination in the United States, most studies evaluating pediatric herpes zoster (HZ) incidence reported lower incidence over time, with varying degrees of decline. Using the combined databases of 6 integrated health care organizations, we examined HZ incidence in children over a 12-year period in the varicella vaccine era.

METHODS

This study included children aged 0 through 17 years from 2003 through 2014. Using electronic medical records, we identified HZ cases through International Classification of Diseases, Ninth Revision diagnosis code 053. We calculated HZ incidence rates per 100 000 person years of health plan membership for all children and among children who were vaccinated versus unvaccinated. We calculated rates for the 12-year period and examined temporal trends. Among children who were vaccinated, we compared HZ rates by month and year of age at vaccination.

RESULTS

The study included 6 372 067 children with ≥1 month of health plan membership. For the 12-year period, the crude HZ incidence rate for all subjects was 74 per 100 000 person years, and the rate among children who were vaccinated was 38 per 100 000 person years, which was 78% lower than that among children who were unvaccinated (170 per 100 000 person years; P < .0001). Overall HZ incidence declined by 72% (P < .0001) from 2003 through 2014. Annual rates in children who were vaccinated were consistently lower than in children who were unvaccinated.

CONCLUSIONS

With this population-based study, we confirm the decline in pediatric HZ incidence and the significantly lower incidence among children who are vaccinated, reinforcing the benefit of routine varicella vaccination to prevent pediatric HZ.

The impact of childhood varicella vaccination on the incidence of herpes zoster in the general population: modelling the effect of exogenous and endogenous varicella-zoster virus immunity boosting

Background

A controversy exists about the potential effect of childhood varicella vaccination on Herpes Zoster (HZ) incidence. Mathematical models projected temporary HZ incidence increase after vaccine introduction that was not confirmed by real-world evidence. These models assume that absence of contacts with infected children would prevent exogenous boosting of Varicella-Zoster-Virus (VZV) immunity and they do not include an endogenous VZV immunity-boosting mechanism following asymptomatic VZV reactivation. This study aims to explore the effect of various assumptions on exogenous and endogenous VZV immunity-boosting on HZ incidence in the general population after introduction of routine childhood varicella vaccination.

Methods

An age-structured dynamic transmission model was adapted and fitted to the seroprevalence of varicella in France in absence of vaccination using the empirical contact matrix. A two-dose childhood varicella vaccination schedule was introduced at 12 and 18 months. Vaccine efficacy was assumed at 65%/95% (dose 1/dose 2), and coverage at 90%/80% (dose 1/dose 2). Exogenous boosting intensity was based on assumptions regarding HZ-immunity duration, age-dependent boosting effect, and HZ reactivation rates fitted to observed HZ incidence. Endogenous boosting was the same as pre-vaccination exogenous boosting but constant over time, whilst exogenous boosting depended on the force of infection. Five scenarios were tested with different weightings of exogenous (Exo) - endogenous (Endo) boosting: 100%Exo–0%Endo, 75%Exo–25%Endo, 50%Exo–50%Endo, 25%Exo–75%Endo, 0%Exo–100%Endo.

Results

HZ incidence before varicella vaccination, all ages combined, was estimated at 3.96 per 1000 person-years; it decreased by 64% by year 80 post vaccine introduction, for all boosting assumptions. The 100%Exo-0%Endo boosting scenario, predicted an increase in HZ incidence for the first 21 years post vaccine introduction with a maximum increase of 3.7% (4.1/1000) at year 9. However, with 0%Exo-100%Endo boosting scenario an immediate HZ decline was projected. The maximum HZ incidence increases at 10, 3, and 2 years post vaccination were 1.8% (75%Exo-25%Endo), 0.8% (50%Exo-50%Endo) and 0.2% (25%Exo-75%Endo), respectively.

Conclusions

Assuming modest levels of endogenous boosting, the increase in HZ incidence following childhood varicella vaccination was smaller and lasted for a shorter period compared with 100%Exo-0%Endo boosting assumption. Endogenous boosting mechanism could partly explain the divergence between previous HZ-incidence projections and real-world evidence.

Electronic supplementary material

The online version of this article (10.1186/s12879-019-3759-z) contains supplementary material, which is available to authorized users.

Implementing Universal Varicella Vaccination in Europe: The Path Forward

Varicella is a common vaccine-preventable disease that usually presents as a mild disorder but can lead to severe complications. Before the implementation of universal varicella vaccination (UVV) in some European countries, the burden of varicella disease was broadly similar across the region. Despite this, countries adopted heterogeneous varicella vaccination strategies. UVV is currently recommended in 12 European countries. Known barriers to UVV implementation in Europe include (1) a perceived low disease burden and low public health priority; (2) cost-effectiveness and funding availability; (3) concerns related to a shift in varicella disease and incidence of herpes zoster and (4) safety concerns related to measles, mumps, rubella and varicella-associated febrile seizures after the first dose. Countries that implemented UVV experienced decreases in varicella incidence, hospitalizations and complications, showing overall beneficial impact. Alternative strategies targeting susceptible individuals at higher risk of complications have been less effective. This article discusses ways to overcome the barriers to move varicella forward as a truly vaccine preventable disease.

[Results of laser confocal microscopy of the cornea in viral uveitis (a preliminary report)]

Herpesviruses involve neurotropic activity (they affect nerve cells) and have the ability to induce an immune response (a special tropism for immune tissue), which provides a valid reason for studying the possibilities of visualizing nerve fibers of the cornea and Langerhans cells (LC) in viral uveitis (with prospective applications in early diagnosis).

PURPOSE

To evaluate the results of laser corneal confocal microscopy (CCM) in viral uveitis of varying localization.

MATERIAL AND METHODS

The main study group included 23 patients (23 eyes) diagnosed with unilateral herpesviral uveitis (chorioretinitis), the patients' age varied from 18 to 79 years. The control group comprised 19 healthy volunteers (38 eyes) aged 20 to 75 years. In addition, the paired eyes of the main group patients were examined. In all patients, standard ophthalmologic examination was complemented with CCM performed on the HRT III device with a corneal module, followed by analysis of the course and structure of corneal nerve fibers (CNF) using copyrighted software Liner 1.2.

CONCLUSION

The preliminary results achieved in this study outline the prospects for further research on the state of cornea (in particular, changes in the course and structure of CNF, and the presence of dendritiform cells of Langerhans) with laser CCM in patients with uveitis of various etiologies. These morphological changes also has potential use as diagnostic markers of inflammation of the uveal tract. The main criteria for assessing the state of cornea in viral uveitis include the following: increased tortuosity of CNF, increase in the number and size of Langerhans cells. Further research - in particular, studying the integrated use of diagnostic methods necessary for the verification of viral uveitis, as well as detailed analysis of the history and clinical picture of the disease - is required to substantiate the inclusion of laser confocal microscopy method in the algorithm for the diagnosis of viral uveitis.

Herpes Zoster Burden in Canadian Provinces: A Narrative Review and Comparison with Quebec Provincial Data

Background

The main aim of this review was to assess incidence rates and trends of medically attended and death cases of herpes zoster in Canada.

Methods

The search was conducted in five databases (PubMed, Cochrane, Embase, PsycNET, and Web of Science). Data on herpes zoster-related consultations and hospitalisations and deaths were also extracted from three Quebec provincial administrative databases (RAMQ, MED-ECHO, and ISQ).

Results

The electronic search yielded 587 publications. Seventeen publications satisfied inclusion criteria. These publications reported data from eleven studies. Ten studies used provincial databases, and one study used the Canadian Primary Care Sentinel Surveillance Network electronic database. Seven studies evaluated overall rates of medically attended cases (consultations and hospitalisations). Four of these studies reported an increase in rates of medically attended cases during the study period; one study reported stable rates, and two studies reported only an average rate. The rates varied from 316 to 450/100,000 p.y. The Quebec analysis shows similar rates with a slight decreasing trend (from 369 to 350/100,000 p.y.). Incidence rates of consultations were reported separately in three studies. Two studies reported an increase in rates (from 258 to 348/100,000 p.y. and from 324 to 366/100,000 p.y.), and the third study reported a decrease (from 525 to 479/100,000 p.y.). Hospitalization rates were reported separately in two studies, both reporting a decrease (from 12 to 8 cases/100,000 p.y. and from 9 to 4 cases/100,000 p.y.). Quebec data also showed a decrease, from 9 to 6 cases/100,000 p.y. One study reported herpes zoster-related deaths. In this study, the reported death rate was 0.7/1,000,000 p.y. in the overall population and 5.5/1,000,000 p.y. in those aged ≥65 years. Quebec analysis showed a death rate of 1.2/1,000,000 p.y. in the overall population and 8.6/1,000,000 p.y. in those aged ≥65 years.

Conclusions

The results of the reviewed studies and our analysis of Quebec provincial data indicate important variations in the reported overall incidence rates of medically attended herpes zoster cases in Canada. The trends in time are heterogeneous in studies in which hospitalisations and medical consultations were pooled together. We observed a decrease in hospitalization rates and a slight increase in consultation rates in studies reporting hospitalisations and consultations separately. These results consolidate the understanding of the herpes zoster burden in Canada and might be used as a tool in decision-making regarding future preventive interventions.

Summary of the NACI Update on Herpes Zoster Vaccines

BACKGROUND

Steep increases in herpes zoster (HZ) incidence, hospitalization due to HZ and the risk of post-herpetic neuralgia as a complication of HZ occur in people over 50 years of age. Two HZ vaccines are currently authorized for use in those 50 years of age and older in Canada: a live attenuated zoster vaccine (LZV) authorized in 2008; and a recombinant subunit vaccine (RZV) authorized in October 2017.

OBJECTIVES

To review current evidence and develop guidance on whether the previously authorized LZV (Zostavax®) and/or the recently authorized RZV (Shingrix®) vaccine should be offered to Canadians 50 years of age and older: 1) at a population-level, in publicly funded immunization programs; and 2) at an individual-level, to individuals wishing to prevent HZ, or by clinicians wishing to advise individual patients about preventing HZ.

METHODS

The National Advisory Committee on Immunization (NACI) Herpes Zoster Working Group developed a predefined search strategy to identify all eligible studies, assessed their quality, and summarized and analyzed the findings. A Cost Utility Analysis of LZV and RZV was also conducted from a health care system perspective. Recommendations were proposed according to NACI's evidence-based process. The strength of these recommendations was defined, and the Grade of evidence supporting them was identified. In light of the evidence, the recommendations were then considered and approved by NACI.

RESULTS

Five recommendations were developed for public health and individual-level decision-making. 1) RZV should be offered to populations/individuals >50 years of age without contraindications (Strong NACI Recommendation, Grade A evidence). 2) RZV should be offered to populations/individuals >50 years of age without contraindications who have previously been vaccinated with LZV (Strong NACI Recommendation, Grade A evidence). Re-immunization with two doses of RZV may be considered one year after LZV (Discretionary NACI Recommendation, Grade I evidence). 3) RZV should be offered to populations/individuals >50 years of age without contraindications who have had a previous episode of HZ (Strong NACI Recommendation, Grade B evidence). Immunization with two doses of RZV may be considered one year after the HZ episode (Discretionary NACI Recommendation, Grade I evidence). 4) LZV may be considered for immunocompetent populations/individuals >50 years of age without contraindications when RZV is contraindicated, unavailable or inaccessible (Discretionary NACI Recommendation, Grade A evidence). 5) RZV (not LZV) may be considered in immunocompromised adults >50 years of age on a case-by-case basis (Discretionary NACI Recommendation, Grade I evidence).

CONCLUSION

Both vaccines have been shown to be safe and immunogenic and to reduce the incidence of HZ and post-herpetic neuralgia. Vaccine efficacy of LZV against HZ decreases with age at, and time since vaccination. The vaccine efficacy of RZV remains higher and appears to decline more slowly than vaccine efficacy of LZV across all age groups. Both vaccines are cost-effective in those 50 years of age and older compared with no vaccination, especially in those 65-79 years of age. RZV is more cost-effective than LZV.

Does herpes zoster predispose to giant cell arteritis: a geo-epidemiologic study

Purpose

Giant cell arteritis (GCA) is the most common systemic vasculitis in the elderly and can cause irreversible blindness and aortitis. Varicella zoster (VZ), which is potentially preventable by vaccination, has been proposed as a possible immune trigger for GCA, but this is controversial. The incidence of GCA varies widely by country. If VZ virus contributes to the immunopathogenesis of GCA we hypothesized that nations with increased incidence of GCA would also have increased incidence of herpes zoster (HZ). We conducted an ecologic analysis to determine the relationship between the incidence of HZ and GCA in different countries.

Methods

A literature search for the incidence rates (IRs) of GCA and HZ from different countries was conducted. Correlation and linear regression was performed comparing the disease IR of each country for subjects 50 years of age or older.

Results

We found the IR for GCA and HZ from 14 countries. Comparing the IRs for GCA and HZ in 50-year-olds, the Pearson product-moment correlation (r) was −0.51, with linear regression coefficient (β) −2.92 (95% CI −5.41, −0.43; p=0.025) using robust standard errors. Comparing the IRs for GCA and HZ in 70-year-olds, r was −0.40, with β −1.78, which was not statistically significant (95% CI −4.10, 0.53; p=0.12).

Conclusion

Although this geo-epidemiologic study has potential for aggregation and selection biases, there was no positive biologic gradient between the incidence of clinically evident HZ and GCA.

Risk Factors for Herpes Zoster: A Systematic Review and Meta-analysis

OBJECTIVE

To systematically review studies examining risk factors for herpes zoster (HZ).

METHODS

We performed a literature search using PubMed, EMBASE, and Web of Science for articles published from January 1, 2003, to February 1, 2017. A random-effects model was used to summarize the risk ratio (RR) or odds ratio (OR) and 95% CI.

RESULTS

Of the 3450 studies screened, we included 84 studies in the systematic review and conducted meta-analysis in 62 studies. Women were at increased risk of HZ compared with men (pooled adjusted RR, 1.31; 95% CI, 1.27-1.34). Black individuals had almost half the risk of HZ as white individuals (pooled RR, 0.54; 95% CI, 0.47-0.63). Family history was found to be a risk factor for HZ (pooled OR, 3.59; 95% CI, 2.39-5.40). Autoimmune diseases, including rheumatoid arthritis (pooled RR, 1.67; 95% CI, 1.41-1.98) and systemic lupus erythematosus (pooled RR, 2.10; 95% CI, 1.40-3.15), were associated with an elevated risk of HZ. Other comorbidities were associated with an increased risk of HZ, with the pooled RRs ranging from 1.25 (95% CI, 1.13-1.39) for asthma to 1.30 (95% CI, 1.17-1.45) for diabetes mellitus and 1.31 (95% CI, 1.22-1.41) for chronic obstructive pulmonary disease.

CONCLUSION

Our review revealed that female sex, race/ethnicity, family history, and comorbidities are risk factors for HZ. Efforts are needed to increase the uptake of zoster vaccination.

Varicella vaccination - the global experience

INTRODUCTION

Varicella, although a frequently benign childhood disease, nevertheless represents a considerable health burden. WHO recommends including varicella vaccines in universal routine vaccination programs, and maintaining coverage >80%. Many countries have successfully introduced varicella vaccination and have benefited from lower disease burden, but many others have not adopted the vaccine. Reasons include cost commitment for a 'mild childhood disease' or concerns that vaccination will shift varicella to older age groups or increase herpes zoster incidence. Areas covered: This literature review summarizes the effectiveness and epidemiological impact of varicella immunization programs. Expert commentary: Varicella vaccines are immunogenic with acceptable safety profiles. One and two dose schedules are highly effective against varicella and large reductions in disease incidence, particularly moderate-severe disease, have been widely reported. There is currently no evidence to suggest that the introduction of varicella vaccination results in a shift of varicella disease burden to older age groups. Although epidemiological studies have shown an increased incidence of herpes zoster since the vaccines were launched, there are many other contributing factors, and indeed, this secular trend was evident before their introduction. In conclusion, varicella vaccination easily fits into existing immunization programs and significantly reduces the often underestimated burden of varicella.

Cost of shingles: population based burden of disease analysis of herpes zoster and postherpetic neuralgia

Background

Around 30% of the population will experience herpes zoster (HZ), 10% of whom develop postherpetic neuralgia (PHN). Together, these illnesses produce a significant economic burden to the healthcare system.

Methods

Administrative healthcare data collected over the period of April 1^st 1997 to March 31^st 2014 were analyzed to determine the healthcare system burden of HZ using direct medical costs. Episodes of HZ were identified using international classification of disease (ICD) codes. Trends in age-adjusted (AA) HZ-rates were analyzed by piecewise-regression. Total annual and per-episode costs were determined for drug treatment, medical care, and hospitalizations within each year.

Results

The incidence of HZ increased by 49.5% from 1997/98 to 2013/14. Piecewise-regression of AA-rates revealed a steady AA-rate of 4.7 episodes/1000 person-years (PY) from 1997/98 to a breakpoint in 2008/09, after which rates began to increase reaching 5.7 episodes/1000 PY in 2013/14.

Drug costs rose significantly (p <0.03) from $89.77/episode (95% CI: $82.96, $96.59) to $127.34/episode (95% CI: $117.24, $137.44). Medical costs increased (p <0.0001) from $57.98/episode (95% CI; $55.26, $60.70) to $78.84/episode (95% CI; $74.08, $83.61). Hospitalization rates declined from 3.10% in 1997/98 to 1.36% in 2011/12, resulting in cost dropping from $397/episode (95% CI; $284, $511) to $195/episode (95% CI; $129, $260).

Total annual costs of HZ and PHN were $1,997,183 in 2011/12, 4.7% lower than the 1997/98 costs of $2,095,633.

Conclusion

A significant increase in annual number of HZ cases was observed, driven largely by demographic factors. A 21% increase in the AA-incidence reveals changes in HZ rates beyond those expected by population shifts.

The large increase in incidence of HZ, with rising per episode medical and prescription costs were offset by dramatic drops in hospitalization rates, the net effect of which has been to hold the total costs relatively constant. However, the decrease in hospitalization rates slowed over the last half of the study, settling at 1.3% in the last 4 study years. The likely future of HZ burden is one of rising costs, primarily driven by the demographic shifts of an increasing and aging population.

Increasing incidence associated with herpes zoster infection in British Columbia, Canada

BACKGROUND

Recent studies have shown an increasing incidence of herpes zoster (HZ) infection, which may be related to the introduction of varicella vaccination programs in children. We examined the epidemiology and treatment costs of HZ and post-herpetic neuralgia (PHN) over time in British Columbia, Canada.

METHODS

The cohort consisted of all cases with HZ infection from January 1, 1997 and December 31, 2012. Incident zoster was defined as a case (ICD-9 053 or ICD-10 B02) without a previous episode of HZ or PHN in the previous 12 months. We determined the incidence for HZ and PHN and the age-sex standardized rate for the overall population. We determined the association between the varicella vaccination program and increased HZ rates by evaluating the rate ratios in the publicly-funded varicella vaccine period compared to the non-publicly funded period in a regression model. We evaluated the hospitalization rates, treatment by GPs and their associated yearly costs for HZ and PHN.

RESULTS

HZ incidence increased for the entire study period from 3.2 per 1000 population in 1997 to 4.5 in 2012. HZ rates were higher for females than males and all age groups had an increased incidence rate, except the 0-9 year olds, where the rate decreased. Crude and age-sex standardized incidence rates of PHN demonstrated very similar patterns to HZ incidence. Based on the regression model, rates of HZ were higher in the older individuals. No significant increase with HZ incidence was seen during the publically funded varicella vaccination program compared to the non-publicly funded period. From 1997 to 2012, the annual HZ-related costs associated with hospitalizations and GP visits were over $CDN4.9 million and $CDN537,286, respectively; treatment costs for hospitalizations have increased significantly over time. Majority of PHN-related cases are managed by GPs, with a steady increase over time in number of cases and associated annual costs.

CONCLUSIONS

The incidence of zoster and PHN is increasing with time, particularly in the elderly population and the risk is greater in the over 65 year olds. Treatment costs for both HZ and PHN represent a significant burden on the Canadian healthcare system.

Price of pain: population-based cohort burden of disease analysis of medication cost of herpes zoster and postherpetic neuralgia

Background

Pain is a main symptom of herpes zoster (HZ), and postherpetic neuralgia (PHN) is a frequent complication occurring in 5% to 15% of cases, causing moderate to severe neuropathic pain. A population-based observational study was conducted to evaluate the treatment patterns and economic burden of prescription drug treatment of HZ and PHN pain in the province of Manitoba (Canada) over a period of 15 years.

Methods

Administrative health care data, including medical and hospital separation records, were examined to identify episodes of HZ using International Classification of Diseases-9/10 codes between April 1, 1997 and March 31, 2014. Episodes of PHN were identified using medical and prescription claims. Incident use of analgesic, antidepressant, or anticonvulsant drugs was used to determine prescription pain costs.

Results

The age-adjusted incidence of HZ increased from 4.7 episodes/1,000 person-years in 1997/98 to 5.7/1,000 person-years in 2013/14. PHN occurred in 9.2% of HZ cases, a rate that did not change over the study period (P=0.57). The annual cost to treat HZ pain rose by 174% from 1997/98, reaching CAD $332,981 in 2011/12, 82.8% (95% confidence interval [CI] 81.2%, 84.3%) of which was related to PHN. The per episode cost of HZ rose by 111% from $31.59 (95% CI $25.35, $37.84) to $66.81 (95% CI $56.84, $76.78) and by 94% for PHN from $292 (95% CI $225, $358) to $566 (95% CI $478, $655). These increases were driven by increasing use of anticonvulsants, primarily gabapentin, which accounted for 57% of the increase in cost.

Conclusion

There has been an increase in the incidence of HZ and PHN and in the average cost associated with the prescription treatment of their resultant neuropathic pain. The primary driver of the increased episodic cost is the increased use of gabapentin. These changes have resulted in a substantial increase in the economic burden associated with HZ and PHN.

Vaccine-preventable disease-related hospitalization among immigrants and refugees to Canada: Study of linked population-based databases

While immigrants tend to be healthier especially when they first arrived, this healthy immigrant effect may not apply to vaccine-preventable diseases (VPD) especially among immigrants from countries without vaccination programs. There is therefore an important information gap regarding differential health outcome and hospitalization usage by immigrant status, landing cohort, world region and immigrant category. This study focused on acute-care hospitalization, and used two recently linked population-based databases in Canada, namely, the 2006 Census linked to the Hospital Discharge Abstract (DAD), and the Immigrant Landing File linked to the DAD (ILF-DAD) to estimate crude and age-standardized VPD-related hospitalization rates (ASHR) by the above-mentioned immigrant characteristics to be compared with that for overall Canadian-born reference population. Based on the 2006 Census-DAD linked database, VPD-specific ASHR for overall immigrants was significantly higher than that for the Canadian-born population (1.6, 95% CI, 1.5, 1.6 vs 1.2, 95% CI, 1.1, 1.2, respectively). VPD-specific ASHRs by landing cohorts also increased with years in Canada (e.g. 1.4, 95% CI, 1.3, 1.5 for the 1990-2006 cohort, and 1.6, 95% CI, 1.5, 1.7 for the pre-1980 cohort). Based on the 1980-2006 ILF-DAD, the VPD-specific ASHRs were highest among Southeast and East Asians (e.g. 2.1, 95% CI, 1.9, 2.3 for East Asia). Compared with the Canadian-born, economic class immigrants overall had significantly lower ASHR (1.4, 95% CI 1.2, 1.6), but the low rate was mainly due to the dependants (spouse or children) within this class (0.8, 95% CI 0.6, 1.1). Both family and refugee categories had significantly higher ASHRs (1.3, 95% CI, 1.2, 1.5 and 1.7, 95% CI, 1.4, 2.1, respectively), especially among those refugees assisted by government (2.0, 95% CI, 1.4, 2.6). With increasing immigration, changing source countries and emerging needs for refugee settlements in Canada, these newly linked datasets help to monitor VPD-related hospitalization pattern among Canadian immigrants.

The changing landscape of antiviral treatment of herpes zoster: a 17-year population-based cohort study

BACKGROUND

Herpes zoster (HZ) is a common viral disease that produces a painful vesicular rash. Early use of antiviral medications is recommended, as it reduces pain and speeds healing. A population-based observational study was conducted to evaluate the changing burden of HZ in the province of Manitoba (Canada) over a period of 17 years.

METHODS

Administrative health care data including medical and hospital records were examined, and International Classification of Diseases, Ninth Revision, Clinical Modification and International Classification of Diseases, Tenth Revision, Clinical Modification codes were used to identify episodes of HZ between April 1, 1997 and March 31, 2014 in persons aged 20 or over. Annual age-adjusted incidence and hospitalization rates were calculated. Prescription records of HZ-diagnosed persons for acyclovir, valacyclovir, and famciclovir were used to calculate the rates and costs of antiviral treatment.

RESULTS

There were 73,893 identified cases of HZ and 1,245 HZ-related hospitalizations between 1997 and 2013. Of these episodes, 42,270 (57.2%) were treated with antiviral medications at a total cost of $4,708,065 (CAD). The age-adjusted incidence of HZ rose from 4.67/1,000 person years in 1997/1998 to 5.67/1,000 person years in 2013/2014, a 21.9% increase. Antiviral treatment rates increased from 41.7% to 66.2% of all diagnosed episodes. Mean treatment costs per episode dropped from $127.29 in 1997/1998 to $56.06 in 2013/2014, primarily due to the introduction of generic antiviral medications. The total cost of antiviral treatment peaked in 2005/2006 at $329,935 and dropped steadily thereafter to $223,973 in 2013/2014. HZ-related hospitalization rates decreased from 3.1% to 0.9%.

CONCLUSION

While both the incidence of HZ and the rates of antiviral treatment have risen substantially, the economic burden from antiviral treatment has been decreasing since a peak in 2005/2006 and was only 3.2% higher in 2013/2014 than in 1997/1998. This drop in cost is attributed to the introduction of generic antiviral drugs.

Increasing Incidence of Herpes Zoster Over a 60-year Period From a Population-based Study

BACKGROUND

Temporal increases in the incidence of herpes zoster (HZ) have been reported but studies have examined short study periods, and the cause of the increase remains unknown. We examined the long-term trend of HZ.

METHODS

A population-based cohort study was conducted in Olmsted County, Minnesota, using data from 1945-1960 and 1980-2007. Medical records review of possible cases was performed to confirm incident cases of HZ, the patient's immune status, and prescribing of antivirals for HZ. We examined the relative change in the temporal trend in the incidence rates before and after the introduction of the varicella vaccination program.

RESULTS

Of the 8017 patients with HZ, 58.7% were females and 6.6% were immunocompromised. The age- and sex-adjusted incidence rate of HZ increased from 0.76 per 1000 person-years (PY) (95% confidence interval [CI], .63-.89) in 1945-1949 to 3.15 per 1000 PY (95% CI, 3.04-3.26) in 2000-2007. The rate of increase across the time period was 2.5% per year after adjusting for age and sex (adjusted incidence rate ratio, 1.025 [95% CI, 1.023-1.026]; P < .001). The incidence of HZ significantly increased among all age groups and both sexes. We found no change in the rate of increase before vs after the introduction of the varicella vaccination program.

CONCLUSIONS

The incidence of HZ has increased >4-fold over the last 6 decades. This increase is unlikely to be due to the introduction of varicella vaccination, antiviral therapy, or change in the prevalence of immunocompromised individuals.

Dissecting the indirect effects caused by vaccines into the basic elements

Vaccination directly protects vaccinated individuals, but it also has the potential for indirectly protecting the unvaccinated in a population (herd protection). Unintended negative consequences such as the re-manifestation of infection, mainly expressed as age shifts, result from vaccination programs as well. We discuss the necessary conditions for achieving optimal herd protection (i.e., high quality vaccine-induced immunity, substantial effect on the force of infection, and appropriate vaccine coverage and distribution), as well as the conditions under which age shifts are likely to occur. We show examples to illustrate these effects. Substantial ambiguity in observing and quantifying these indirect vaccine effects makes accurate evaluation troublesome even though the nature of these outcomes may be critical for accurate assessment of the economic value when decision makers are evaluating a novel vaccine for introduction into a particular region or population group. More investigation is needed to identify and develop successful assessment methodologies for precisely analyzing these outcomes.

Twenty Years of Medically-Attended Pediatric Varicella and Herpes Zoster in Ontario, Canada: A Population-Based Study

OBJECTIVE

To determine if reductions in medically-attended pediatric varicella and herpes zoster occurred in Ontario, Canada, after publicly-funded varicella immunization was implemented in 2004.

METHODS

For fiscal years (FY) 1992-2011, we examined data on varicella and herpes zoster physician office visits, emergency department (ED) visits, hospitalizations (including for varicella-associated skin and soft tissue infections [SSTI]), and intensive care unit (ICU) admissions, among those aged <18 years. The pre-vaccine, privately-available, and vaccine program eras were FY1992-1998, FY1999-2003, and FY2004-2011, respectively. We used Poisson regressionand Kruskal-Wallis tests (all at the p<0.05 level of significance), and compared rates using incidence rate ratios (IRRs) and 95% confidence intervals (CIs).

RESULTS

Incidence of varicella office visits declined over the study period from a high of 25.1/1,000 in FY1994 to a low of 3.2/1,000 in FY2011. ED visits and hospitalizations followed similar patterns of decreasing rates later in the study period. IRRs comparing the vaccine program versus pre-vaccine eras were 0.29 (95%CI: 0.26-0.32) for office visits, 0.29 (95%CI: 0.21-0.40) for ED visits, and 0.41 (95%CI: 0.10-1.69) for hospitalizations. Annual declines in varicella office visits were 7.7%, 9.1%, 8.4%, and 8.4% per year among children aged <1 year, 1-4 years, 5-11 years, and ≥12 years, respectively (all p<0.001). Age-specific rates of varicella-associated SSTI declined significantly among children <12 years (p<0.001) and rates of ICU admissions decreased significantly for children <1 year (p = 0.02). (p<0.001) over the study period. For children aged 5-17 years, herpes zoster office visits decreased whereas ED visits increased (both p<0.001) and there was a small, non-significant (p = 0.07), decrease in hospitalizations.

CONCLUSION

Medically-attended varicella decreased during the study period, particularly since varicella vaccine was publicly-funded. Results suggest immunization program-related changes in varicella epidemiology, including herd effects, demonstrated by reductions in varicella in program-ineligible age groups. We did not observe a consistent impact on herpes zoster.

Herpes zoster epidemiology, management, and disease and economic burden in Europe: a multidisciplinary perspective

Herpes zoster (HZ) is primarily a disease of nerve tissue but the acute and longer-term manifestations require multidisciplinary knowledge and involvement in their management. Complications may be dermatological (e.g. secondary bacterial infection), neurological (e.g. long-term pain, segmental paresis, stroke), ophthalmological (e.g. keratitis, iridocyclitis, secondary glaucoma) or visceral (e.g. pneumonia, hepatitis). The age-related increased incidence of HZ and its complications is thought to be a result of the decline in cell-mediated immunity (immunosenescence), higher incidence of comorbidities with age and social-environmental changes. Individuals who are immunocompromised as a result of disease or therapy are also at increased risk, independent of age. HZ and its complications (particularly postherpetic neuralgia) create a significant burden for the patient, carers, healthcare systems and employers. Prevention and treatment of HZ complications remain a therapeutic challenge despite recent advances. This is an overview of the multidisciplinary implications and management of HZ in which the potential contribution of vaccination to reducing the incidence HZ and its complications are also discussed.

Epidemiology of pediatric herpes zoster after varicella infection: a population-based study

BACKGROUND

There are limited population-based data regarding pediatric herpes zoster (HZ).

METHODS

Children aged <12 years with varicella infections between 2000 and 2006 were identified from a national population-based database and followed-up for a diagnosis of HZ until December 2008. Since a routine varicella vaccination program was started in 2004, vaccinated children without medically attended varicella were identified between 2004 and 2006, and followed-up for a diagnosis of HZ until December 2008.

RESULTS

Of 27 517 children with medically attended varicella, 428 developed HZ. The incidence of HZ was 262.1 per 100 000 person-years. Of 25 132 vaccinated children without medically attended varicella, 106 developed HZ. The incidence of HZ was 93.3 per 100 000 person-years. The mean duration from varicella to HZ was 4.12 years. Children diagnosed with varicella at aged <2 years had a higher incidence (P < .001) and shorter duration (P = .04) than those diagnosed aged ≧2 years. Children diagnosed with varicella aged ≥2 but <8 years had a significantly increased incidence of HZ after than before the vaccination program (relative risk = 1.85 at 3 years of follow-up, P = .03). Children with varicella infections had a significantly greater risk of HZ than vaccinated children without a history of varicella (relative risk = 2.31 at 4 years of follow-up, P < .001).

CONCLUSIONS

This study demonstrates the population-based epidemiologic characteristics of pediatric HZ among those who contracted varicella. In the early postvaricella vaccination period, an increased HZ incidence was observed among children with varicella infection aged ≥2 years.

Successes and challenges in varicella vaccine

Varicella is a highly contagious disease caused by primary infection with varicella zoster virus (VZV). VZV infection, as well as varicella vaccination, induces VZV-specific antibody and T-cell-mediated immunity, essential for recovery. The immune responses developed contribute to protection following re-exposure to VZV. When cell-mediated immunity declines, as occurs with aging or immunosuppression, reactivation of VZV leads to herpes zoster (HZ). It has been almost 20 years since universal varicella vaccination has been implemented in many areas around the globe and this has resulted in a significant reduction of varicella-associated disease burden. Successes are reviewed here, whilst emphasis is put on the challenges ahead. Most countries that have not implemented routine childhood varicella vaccination have chosen to vaccinate high-risk groups alone. The main reasons for not introducing universal vaccination are discussed, including fear of age shift of peak incidence age and of HZ incidence increase. Possible reasons for not observing the predicted increase in HZ incidence are explored. The advantages and disadvantages of universal vs targeted vaccination as well as different vaccination schedules are discussed.

Varicella and herpes zoster hospitalizations before and after implementation of one-dose varicella vaccination in Australia: an ecological study

OBJECTIVE

To examine trends in varicella and herpes zoster (HZ) hospitalization following the availability and subsequent National Immunization Programme funding of one-dose varicella vaccination in Australia.

METHODS

Varicella vaccination coverage for children born between 2001 and 2009 was obtained from the Australian Childhood Immunization Register. Principal or any coded varicella or HZ hospitalizations were retrieved from the national hospital morbidity database from 1998 to 2010. Trends in hospitalization rates in different age groups and indigenous status were assessed. Incidence rate ratios (IRR) were calculated between periods before and after implementation of immunization programme funding.

FINDINGS

In the first year of the funded immunization programme, varicella vaccine coverage reached 75% in children aged 24 months and more than 80% in children aged 60 months. Compared with the pre-vaccine period, varicella hospitalization rates during the funded programme were significantly lower for age groups younger than 40 years; with the greatest reduction in children aged 18-59 months (IRR: 0.25; 95% confidence interval, CI: 0.22-0.29). Indigenous children had a higher varicella hospitalization rate compared with non-indigenous children before vaccine implementation (IRR: 1.9; 95% CI: 1.4-2.7), but afterwards reached equivalence (IRR: 1.1; 95% CI: 0.7-1.6). The age-standardized HZ hospitalization rate declined between the periods (IRR: 0.95; 95% CI: 0.92-0.97).

CONCLUSION

Rapid attainment of high coverage reduced varicella hospitalizations in the targeted age group, particularly for indigenous children, but also in non-targeted age groups, with no increase in HZ hospitalizations. This suggests high one-dose varicella vaccine coverage can have a substantial impact on severe disease.

Systematic review of incidence and complications of herpes zoster: towards a global perspective

OBJECTIVE

The objective of this study was to characterise the incidence rates of herpes zoster (HZ), also known as shingles, and risk of complications across the world.

DESIGN

We systematically reviewed studies examining the incidence rates of HZ, temporal trends of HZ, the risk of complications including postherpetic neuralgia (PHN) and HZ-associated hospitalisation and mortality rates in the general population. The literature search was conducted using PubMed, EMBASE and the WHO library up to December 2013.

RESULTS

We included 130 studies conducted in 26 countries. The incidence rate of HZ ranged between 3 and 5/1000 person-years in North America, Europe and Asia-Pacific, based on studies using prospective surveillance, electronic medical record data or administrative data with medical record review. A temporal increase in the incidence of HZ was reported in the past several decades across seven countries, often occurring before the introduction of varicella vaccination programmes. The risk of developing PHN varied from 5% to more than 30%, depending on the type of study design, age distribution of study populations and definition. More than 30% of patients with PHN experienced persistent pain for more than 1 year. The risk of recurrence of HZ ranged from 1% to 6%, with long-term follow-up studies showing higher risk (5-6%). Hospitalisation rates ranged from 2 to 25/100 000 person-years, with higher rates among elderly populations.

CONCLUSIONS

HZ is a significant global health burden that is expected to increase as the population ages. Future research with rigorous methods is important.

Influence of frequent infectious exposures on general and varicella-zoster virus-specific immune responses in pediatricians

Reexposure to viruses is assumed to strengthen humoral and cellular immunity via the secondary immune response. We studied the effects of frequent exposure to viral infectious challenges on immunity. Furthermore, we assessed whether repetitive exposures to varicella-zoster virus (VZV) elicited persistently high immune responses. Blood samples from 11 pediatricians and matched controls were assessed at 3 time points and 1 time point, respectively. Besides the assessment of general immunity by means of measuring T-cell subset percentages, antibody titers and gamma interferon (IFN-γ)/interleukin 2 (IL-2)-producing T-cell percentages against adenovirus type 5 (AdV-5), cytomegalovirus (CMV), tetanus toxin (TT), and VZV were determined. Pediatricians had lower levels of circulating CD4(+)-naive T cells and showed boosting of CD8(+) effector memory T cells. Although no effect on humoral immunity was seen, repetitive exposures to VZV induced persistently higher percentages of IFN-γ-positive T cells against all VZV antigens tested (VZV glycoprotein E [gE], VZV intermediate-early protein 62 [IE62], and VZV IE63) than in controls. T cells directed against latency-associated VZV IE63 benefitted the most from natural exogenous boosting. Although no differences in cellular or humoral immunity were found between the pediatricians and controls for AdV-5 or TT, we did find larger immune responses against CMV antigens in pediatricians. Despite the high infectious burden, we detected a robust and diverse immune system in pediatricians. Repetitive exposures to VZV have been shown to induce a stable increased level of VZV-specific cellular but not humoral immunity. Based on our observations, VZV IE63 can be considered a candidate for a zoster vaccine.

Cost-effectiveness of vaccination against herpes zoster

Herpes zoster (HZ) is a common disease among elderly, which may develop into a severe pain syndrome labeled postherpetic neuralgia (PHN). A live-attenuated varicella zoster virus vaccine has been shown to be effective in reducing the incidence and burden of illness of HZ and PHN, providing the opportunity to prevent significant health-related and financial consequences of HZ. In this review, we summarize the available literature on cost-effectiveness of HZ vaccination and discuss critical parameters for cost-effectiveness results. A search in PubMed and EMBASE was performed to identify full cost-effectiveness studies published before April 2013. Fourteen cost-effectiveness studies were included, all performed in western countries. All studies evaluated cost-effectiveness among elderly above 50 years and used costs per quality-adjusted life year (QALY) gained as primary outcome. The vast majority of studies showed vaccination of 60- to 75-year-old individuals to be cost-effective, when duration of vaccine efficacy was longer than 10 years. Duration of vaccine efficacy, vaccine price, HZ incidence, HZ incidence and discount rates were influential to the incremental cost-effectiveness ratio (ICER). HZ vaccination may be a worthwhile intervention from a cost-effectiveness point of view. More extensive reporting on methodology and more detailed results of sensitivity analyses would be desirable to address uncertainty and to guarantee optimal comparability between studies, for example regarding model structure, discounting, vaccine characteristics and loss of quality of life due to HZ and PHN.

Examination of links between herpes zoster incidence and childhood varicella vaccination

BACKGROUND

Introduction of a universal varicella vaccine program for U.S. children in 1996 sparked concern that less-frequent exposure to varicella would decrease external boosting of immunity to varicella zoster virus and thereby increase incidence of herpes zoster (HZ).

OBJECTIVE

To determine whether the varicella vaccination program has influenced trends in HZ incidence in the U.S. population older than 65 years.

DESIGN

Retrospective study of Medicare claims.

SETTING

Medicare, 1992 through 2010.

PARTICIPANTS

2 848 765 beneficiaries older than 65 years.

MEASUREMENTS

Annual HZ incidence from 1992 through 2010; rate ratios (RRs) for HZ incidence by age, sex, and race or ethnicity; and state-level varicella vaccination coverage.

RESULTS

281 317 incident cases of HZ occurred. Age- and sex-standardized HZ incidence increased 39% from 10.0 per 1000 person-years in 1992 to 13.9 per 1000 person-years in 2010 with no evidence of a statistically significant change in the rate of increase after introduction of the varicella vaccination program. Before introduction of this program, HZ incidence was higher in women (RR, 1.21 [95% CI, 1.19 to 1.24]) than men and was lower in black persons (RR, 0.51 [CI, 0.48 to 0.53]) and Hispanic persons (RR, 0.76 [CI, 0.72 to 0.81]) than white persons. In a model adjusted for sex, age, and calendar year from 1997 to 2010, HZ incidence did not vary by state varicella vaccination coverage (RR, 0.9998 [CI, 0.9993 to 1.0003]).

LIMITATION

Uncertain level and consistency of health-seeking behavior and access and uncertain accuracy of disease coding.

CONCLUSION

Age-specific HZ incidence increased in the U.S. population older than 65 years even before implementation of the childhood varicella vaccination program. Introduction and widespread use of the vaccine did not seem to affect this increase. This information is reassuring for countries considering universal varicella vaccination.

PRIMARY FUNDING SOURCE

None.

Epidemiology and cost of herpes zoster and postherpetic neuralgia in Germany

After acquiring a varicella virus infection, the virus can reactivate and cause herpes zoster (HZ)--a painful skin rash. A complication of HZ is long-term persistence of pain after the rash has resolved (so-called postherpetic neuralgia, PHN). We aimed to describe the epidemiology of HZ/PHN and to estimate HZ/PHN-related costs in the German statutory health insurance (SHI) system (~85% of the total population). Treatment data of one large SHI was utilized, containing data on approximately 240,000 insured and their utilisation of services in 2004-2009. Identification of HZ- and PHN-cases was performed based on 'International Statistical Classification of Diseases' and specific medications using a control-group design. Incidences per 1,000 person-years (PY) and cost-of-illness for 1 year following HZ-onset considering the payer and societal perspective were calculated. All amounts were inflated to 2010 Euros. Population-figures were standardised and extrapolated to the total SHI-population in Germany in 2010. A mean annual incidence of 5.79 HZ-cases per 1,000 PY was observed, translating into an estimated 403,625 HZ-cases per year in the total SHI-population. Approximately 5% of HZ-cases developed PHN. One HZ-case caused on average euro 210 and euro 376 of costs from the payer and societal perspective, respectively. The development of PHN generated additional costs of euro 1,123 (euro 1,645 societal perspective). Total annual HZ/PHN-related costs were estimated at euro 182 million (euro 105 million) to society (payer). HZ and PHN place a considerable burden on the German SHI-system. Since HZ-vaccines will soon be available, a health-economic evaluation of these vaccines should be conducted.

Shingles in Alberta: before and after publicly funded varicella vaccination

PURPOSE

A universal publicly funded chickenpox vaccination program was implemented in Alberta in 2002. We examine the epidemiology of medically attended shingles in Alberta from 1994 to 2010.

METHODS

Incident shingles cases (earliest health service utilizations for ICD-9 053 or ICD-10-CA B02) and their co-morbid conditions for the 12 months prior to shingles diagnosis were identified from the records of Alberta's universal, publicly funded health-care insurance system for 1994-2010. Shingles diagnostic codes at least 180 days after the first were classified as recurrent episodes. Denominators for rates were estimated using mid-year population estimates from the Alberta Health Care Insurance Plan Registry. Annual age- and sex-specific rates were estimated. We estimated the proportion of all cases that were hospitalized. We explored the pattern of rates for sex, age-group co-morbidity and year effects and their interactions.

RESULTS

Crude rates of shingles increased over the interval 1994-2010. Most persons had only a single episode of shingles; 4% of cases were hospitalized. Shingles rates were higher among females than males. While only 2% of shingles cases had one or more co-morbidities, this proportion was also higher for females than males. Prior to 2002, all age groups of both sexes experienced increasing annual rates of shingles. However, there was a sharp decline in the rate of shingles for both females and males under the age of 10 years for 2002-2010, the period in which there was publicly funded chickenpox vaccination.

CONCLUSION

The declining rates of shingles among persons under the age of 10 years are consistent with an impact of the chickenpox vaccination program. The trend of increasing rates of shingles among older persons began prior to implementation of vaccination.

Impact of universal two-dose vaccination on varicella epidemiology in Navarre, Spain, 2006 to 2012

In 2007 in Navarre, Spain, universal varicella vaccination with two doses of Varivax was introduced in the childhood immunisation schedule for children aged 15 months and three years. This study describes changes in the epidemiology of varicella in the period 2006 to 2012 and evaluates vaccination effectiveness using epidemiological surveillance data. The incidence of varicella in children aged 0 to 14 years decreased by 98.1%, from 50.1 cases per 1,000 inhabitants in 2006, to 1.0 per 1,000 in 2012. Children aged one to eight years were the vaccinated cohorts, and their incidence of varicella decreased by 98.5% (p<0.0001). In unvaccinated age groups, important reductions were also achieved between 2006 and 2012: 90.5% (p<0.0001) in infants under one year of age, and 89.4% (p<0.0001) in children aged nine years. In the period 2006 to 2012, the hospital admissions rate for varicella or its complications decreased by 89.0%, and in 2012, there was only one admission of a newborn with neonatal varicella. Vaccine effectiveness for at least one dose was 96.8% (95% confidence interval: 96.3-97.2%). Universal vaccination with two doses has reduced varicella circulation to minimum levels within five years and has proved highly effective.

Herpes Zoster Risk Reduction through Exposure to Chickenpox Patients: A Systematic Multidisciplinary Review

Varicella-zoster virus (VZV) causes chickenpox and may subsequently reactivate to cause herpes zoster later in life. The exogenous boosting hypothesis states that re-exposure to circulating VZV can inhibit VZV reactivation and consequently also herpes zoster in VZV-immune individuals. Using this hypothesis, mathematical models predicted widespread chickenpox vaccination to increase herpes zoster incidence over more than 30 years. Some countries have postponed universal chickenpox vaccination, at least partially based on this prediction. After a systematic search and selection procedure, we analyzed different types of exogenous boosting studies. We graded 13 observational studies on herpes zoster incidence after widespread chickenpox vaccination, 4 longitudinal studies on VZV immunity after re-exposure, 9 epidemiological risk factor studies, 7 mathematical modeling studies as well as 7 other studies. We conclude that exogenous boosting exists, although not for all persons, nor in all situations. Its magnitude is yet to be determined adequately in any study field.